Keycloak: keycloak: denial of service due to excessive samlrequest decompression

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Summary

CVECVE-2026-2575
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-18 04:17:16 UTC
Updated2026-06-03 19:36:23 UTC
DescriptionA flaw was found in Keycloak. An unauthenticated remote attacker can trigger an application level Denial of Service (DoS) by sending a highly compressed SAMLRequest through the SAML Redirect Binding. The server fails to enforce size limits during DEFLATE decompression, leading to an OutOfMemoryError (OOM) and subsequent process termination. This vulnerability allows an attacker to disrupt the availability of the service.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.000450000 probability, percentile 0.141350000 (date 2026-06-03)

Problem Types: CWE-409 | CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNACVSS5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Redhat Build Of Keycloak All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Build Of Keycloak 26.4 unaffected 26.4.10-1 * rpm Not specified
CNA Red Hat Red Hat Build Of Keycloak 26.4 unaffected 26.4-12 * rpm Not specified
CNA Red Hat Red Hat Build Of Keycloak 26.4 unaffected 26.4-12 * rpm Not specified
CNA Red Hat Red Hat Build Of Keycloak 26.4.10 Not specified Not specified

References

ReferenceSourceLinkTags
access.redhat.com/errata/RHSA-2026:3947 [email protected] access.redhat.com Vendor Advisory
access.redhat.com/security/cve/CVE-2026-2575 [email protected] access.redhat.com Vendor Advisory
access.redhat.com/errata/RHSA-2026:3948 [email protected] access.redhat.com Vendor Advisory
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com Issue Tracking, Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Red Hat would like to thank Sho Odagiri (GMO Cybersecurity by Ierae, Inc.) for reporting this issue. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-02-16T08:36:10.890ZReported to Red Hat.
CNA2026-02-16T08:08:00.000ZMade public.

Workarounds

CNA: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

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